@Flashman:
I’ve been advocating this 4 power split for years now.
I would add that China should be split between Communist (USSR), Nationalist (western Allies) and Collaborationist (Japanese) forces, with only infantry ever being built in China.
Incidentally, the “red”, & “green” Chinese can fight each other (within China) without causing war between the Western Allies and the Soviets. Similarly they can each fight the Japanese without causing war with that block.
USSR and Japan were not at war until after Hiroshima; it could be argued that the USSR and the Axis were allies until June 1941. But there need be no official alliances between the 4 blocks. Maybe something to prevent a 3 on 1 ganging up? Also, a power cannot call off a war with another block once fighting has started; it is still always a fight to the finish.
Two parties can always call an agreed upon truce. Or you could call and agree to limited wars. (I will only fight your troops in these territories, and you can fight mine in them, if it spills over there are repurcussions). Global 39 has a proxy war over finland that is cause for entertainment.
As for 3 ganging up on 1, it doesn’t happen, because chances are that 1/3 will become so powerful, that 2/3 and 3/3 will want to prevent 1/1 from being eliminated to keep the balance of power.
FFA games, tend to balance themselves to a degree. The only requirement is that you impost a time limit (20 turns) so as to force players to fight, hungergames style.